After the civil wars which brought Augustus to power, on the winning side alone, 60 legions stood combat-ready.
Augustus decided to retain 28, while the remainder would be demobilized and settled in the colonies.
By this act, the west's first standing army of 150'000 legionaries and a similar number of auxiliaries was created. Length of service was set at sixteen years, later it was increased to twenty.
Though his army of 28 legions Augustus made sure to quickly spread across the far reaches of the empire, with all the legions being posted both far away from Rome as well as as far away as possible from each other.
It expressed Augustus' distrust of soldiers and of ambitious men who might rouse them against him.
By keeping the armies close to the borders their energies would be directed outward, toward foreign enemies; and keeping them far from each other would ensure that no overwhelming force could be assembled which might threaten the throne.
While this caution, right after the civil war, was understandable, Augustus' arrangements would long outlive him.
Augustus disposition of the legions was matched by his manipulation of the provinces. Of these he retained the most powerful under his direct power on the grounds that they were insecure, either with enemies on their borders or were themselves capable of rebellion. But his real purpose was that he alone should have arms and maintain soldiers. In short, Augustus kept the outer, returning the inner provinces to the Senate. It was a muted way of assuring himself commander-in-chief, for the army would be stationed only in the outer provinces which would be governed and administered by the emperor's appointees.
This meant that the frontier would be under direct imperial authority, establishing for the emperor a hold over foreign affairs and decisions of peace and war.
The division of territory into 'Senate's share' and 'Caesar's share' was accompanied by a ban on senators even visiting a frontier province without imperial permission.
It was clear from this that Augustus saw the Senate as one of the likeliest sources from which to expect a challenge to his position.
To this one must add, that to Augustus (as well as to later Caesars) the Senate, with its centuries of experience, remained indispensable in running the empire.

The East of the empire gave no trouble. The small dependent kingdoms still surviving in Asia Minor (Turkey) were peacefully and gradually absorbed into the Roman provincial system.
Parthia under king Phraates had no desire to challenge Rome. The unavenged disaster of Carrhae in 53 BC however had always rankled in the Roman mind. So when in 20 BC a demand was made by Rome, emphasized by a military demonstration of force along the border, for the return of the captives and most importantly for the legionary standards, which had been in Parthian possession since the disastrous defeat of Crassus over thirty years earlier. King Phraates wisely gave way, avoiding war against a newly united foe, increasing in strength. The standards were returned to Rome without a fight. An achievement which won Augustus high praise.

By 19 BC Agrippa had assured the submission of the Spanish tribes. But a German incursion across the Rhine in 16 BC defeated a Roman commander, Lollius, and called for the temporary presence of Augustus at the front, where he left the command in the hands of his stepson Drusus.
In 12 BC Agrippa died and with him Augustus lost his most obvious heir. For a while Augustus hoped for Gaius or Lucius, both sons of Agrippa to succeed him, but as they both died his choice somewhat reluctantly fell on Tiberius, the son by his wife out of a previous marriage.
Then followed a conquest of Germany, initially to the Elbe. At first it was led by Drusus, who died on campaign. He was succeeded by Tiberius who had established Roman supremacy over Pannonia and Noricum.
Sixteen years' struggle in mire and forest, amphibious landings and spectacular marches were rewarded with a succession of victories. A bold project, sometimes referred to as the 'Bohemian Plan', was mooted as a culminating blow. Tiberius would cross the Danube heading north, snip off what is now the western end of the Czech Republic, descend into the German plain and join hands with an army group advancing eastwards from the Rhine. The so-called 'Bohemian Plan' may have only been meant as one step in a much larger offensive.
Rome, of course, virtually unbeaten so far and inexorably rising to conquer the word, by now virtually understood the rule of the world its birthright.
But none of these grand schemes would be implemented. Shortly before commencement of operations, a revolt erupted in Tiberius' rear and spread rapidly across the Balkans. To quell it required almost half of Rome's fighting strength, to become tied up for three years in a mountain war.
Meanwhile it was deemed that Northern Germany, west of the Elbe was sufficiently pacified. P. Quintillius Varus was entrusted as governor of the province. Though Germany was not ready for Roman civilization.
In AD 9 disaster struck an empire which until then had virtually met no opponent capable of halting its rise to supreme power.
Under the command of Varus three legions and three cavalry squadrons marched through the Teutoburger Wald (Saltus Teutoburgiensis) The German tribe, the Cherusci, under their leader known to the Romans as Arminius, had learnt their lesson.
In open terrain, with room to manoeuvre, the Roman army was literally unbeatable. But in the middle of a forest, it was vulnerable. The trap was sprung and three entire legions were annihilated. Arminius' victory was a major turning point in the history of the Roman Empire. If Romans had previously marched as far as the Elbe, and even if they could do so in future, then this proved that they would never ever really rule any territory north of the Rhine and the Danube. - Rome had alas met its match in the barbarians of northern Europe.
Though it was a costly lesson for Rome. Three legions had been annihilated. Varus and his staff committed suicide. It was to be remembered by the Romans as the 'Varian disaster'.
Tiberius thereafter still could march his legions through Germany almost unhindered, in fact he did so. But not to subdue it and conquer it. For this, one now understood, was beyond Roman power.
Tiberius was recalled from his task of restoring Roman authority in Germany. Instead command was left in the hands of Germanicus, who was to be highly popular with the legions, in contrast to the almost despised Tiberius.
Had Germanicus had any serious political ambitions he would certainly have become a formidable opponent to any future emperor. Yet, Germanicus was loyal and a devoted soldier.

Alas, Augustus went out with advice to his successors that the empire should be kept within its existing boundaries. This was an astonishing turn of events. The imperialist had recanted. Rome could not expand indefinitely. He had in office learned of the problems facing an empire of this scale and appreciated the difficulties in holding it together.
Any further expansion in the eyes of the elderly Augustus would take the empire beyond being practically governable.
Also, the Mediterranean part of Europe, Africa and Asia, which Rome now ruled had been developed prior to Roman occupation. There was roads, town, cities. What prize was there to win, defeating the barbarian hordes of the north. Augustus ultimate conclusion from the Varian Disaster was that only civilized territories were worth the blood of Roman legionaries.
His advice would have demanded a change in attitude by all Rome - to defend, not to conquer. Rome however, the she-wolf with her mighty legions, was not yet ready for such advice.

When at last the old Augustus died it was a matter of course that the senate, still the nominal governing body, should petition Tiberius to accept the succession, and that he should do so with some reluctance.
The soldiery was loyal to him, the representatives of the great families had neither experience of rule nor military position. Hence his accession went unchallenged.
As under Augustus the empire at large enjoyed peace and prosperity, showing no signs of general disaffection. The provincial system worked under Tiberius, as it had under Augustus, much better than under the old senatorial system.
No little insight and resolution were needed to face imperial problems as Tiberius dealt with agitators, vested interests and upholders of aristocratic tradition, all of whom were united in denouncing him as evil and corrupt.
Though much of Tiberius' bad image in history is due to his own doing. The responsibility for the vicious rule of his administrator Sejanus, the head of the praetorian guard, ultimately lay with the emperor who had chosen him for the job. So too Tiberius' treason laws created an air of terror in Rome. The introduction of a large network of paid informers under Tiberius only further increased the feeling of oppression.

Along the Rhine the troops would no doubt have hailed Germanicus to be the new emperor instead of the despised Tiberius, if only they could have won their champions' consent. But Germanicus remained loyal. His heart was instead set on the conquest of Germany, where he indeed did succeed in inflicting a heavy defeat on Arminius.
Tiberius though conscientiously followed the advice of Augustus in seeking to extend the empire any further and recalled Germanicus from Germany, in AD 17 instead dispatching him to the east. Many saw this as an act of jealousy by the emperor at the time, envious of his general's popularity. While in the east, Germanicus died in circumstances which gave rise to rumours that his death had been designed by Tiberius, and his memory was cherished as a victim of the emperor's jealousy.

In AD 26 Tiberius retired to the island of Caprae (Capri) where he, according to rumour, lived a life of debauchery, leaving Rome in the hands of his praetorian prefect Sejanus.
Though Sejanus, having concentrated the praetorian guard in one camp, whereas before they had been scattered across Rome, was a brutal tyrant, who sought to eventually rid himself of Tiberius and become emperor himself.
Though Sejanus' intentions became apparent to Tiberius and he was stripped of his power and executed in AD 31.

The fall of Sejanus served only to relieve the nightmare, not to end it. For six more years Tiberius remained at Caprae. At last he died in AD 37, most likely murdered by his praetorian prefect Macro in favour of his nephew Caligula.

Caligula was the third son of Germanicus, his two elder brothers were both dead. Now twenty-four years of age, he was the sole contender to the throne. As the son of Germanicus he certainly had the support of the army. His uncle Claudius, the younger brother of Germanicus, was without ambition and was reputed to be feeble-minded, while Gaius was credited with all his father's virtues. He was forthwith acclaimed princeps (first citizen). Augustus on his death had been granted divine honours. Caligula was applauded for refusing them to the dead Tiberius.
For the moment it seemed that better days were in store. Much was to be hoped from a prince who was young, popular and generous - and who began his reign by liberating prisoners, recalling exiles, publicly burning incriminating documents, and showing great determination in the unaccustomed business of administration. But after a few months Caligula fell ill, and he rose from his sickness in effect a madman; bereft of all moral sense but not of that distorted but occasionally acute intelligence which accompanies some forms of mania. The new nightmare was more terrible that that which had passed with Tiberius.

Caligula slew, it might be with some definite reason, it might be merely because he had the fancy to slay, wether from blood-lust or as mere demonstration of power. He inaugurated magnificent public works, and forgot them when the fancy passed. He resolved to conquer Britain, gathered his invasion forces at Boulogne, and then set the men to gather shells on the shore, and these he sent to Rome as the spoils of the conquered ocean. He returned to Rome threatening slaughter because the senate had not been sufficiently zealous in preparing form him a magnificent triumph.
Finally an officer of the praetorians finally summoned up the courage to assassinate him with the aid of a few companions, in the fifth year of his crazed reign (AD 41).

As news of Caligula's assassination spread, the senate gathered in haste, several of them ready to press their own claims to the succession, other urged that the moment had come to restore the republic.
Though the praetorian guard had its own ideas as to who should take the throne. Claudius, Caligula's feeble-minded uncle, had been dragged from his hiding place in the palace to the praetorian camp, where he was promptly hailed as emperor, and then marched back to the senate, who had no choice but to confirm their decision.
But the soldiers had chosen better than they knew. Claudius had spent his life a the almost forgotten, half-witted brother of the great Germanicus. But now in office he proved extremely conscientious. His intentions were excellent, and his political theory, if derived wholly from books, was intelligent. He was 'the wisest fool' in Rome, but he kept his wisdom for the state, while his domestic follies made him a figure of contempt to his contemporaries and ridiculous to posterity.

Claudius was already fifty years old when he began his reign (AD 41- 54). Throughout the period the empire enjoyed general prosperity and there were few complaints from the provinces. Claudius held firmly to the belief that the existing border was to be maintained but not extended.
Military expeditions conducted against the aggressive German tribes of the Chauci and Catti - who had probably absorbed the Cherusci - were completely successful, though not followed by any attempt of annexation.
Within the empire the practice of extending full Roman citizenship to favoured communities was actively developed.
But the main achievement of the reign of Claudius was the organized conquest of the south of Britain.
Had Claudius stayed true to Augustus' advice not to expand the empire, this was the one time he broke with it. Was it either to prove himself worthy to his contemporaries in a bid to shake off his image as a half-wit, or simply because the threat of a largely unknown kingdom off the coast of Gaul was too serious to go unchecked, Claudius in AD 43 sent forth a giant invasion force under the command of Aulus Plautius.
Claudius himself took the field at one time and the entire expedition was resounding military success.
It is however to the credit of Claudius that when the brave Caractacus, the leader of the Britons, was sent to Rome as a captive, he was granted an honourable liberty by the emperor.

But unhappily the feature of Claudius' reign most annoying to the public of the time, was the influence of freedmen, for the most part Greeks, who won his confidence, and by the successive wives who plotted against him while they fooled him as they pleased.
Of the freedmen the most notorious were perhaps Narcissus and Pallas. Their rivalry did not prevent them from working in concert to their common advantage. They quite literally sold public honours and privileges. Though they were men of ability, who rendered useful service when it was in their own interest to do so, forming a sort of imperial secretariat, free of influence by class interests or social prejudices.

In AD 48 Claudius finally rid himself of Messalina, a wife who had disgusted Roman society with her constant betrayal and ridicule of her husband, until alas his eyes had been opened to the fact. The place vacated by Messalina was secured by the emperor's ambitious niece, Agrippina the younger, sister of Caligula, widow of Domitius Ahenobarbus and the mother of the young Nero.
Right from the beginning Agrippina set out to see her son Nero become heir to the imperial throne. Alas he was persuaded to adopt Nero as his own son. Nero being three years the senior to Claudius' own son Britannicus meant that Agrippina had achieved her ambition.
But then as signs became apparent that Claudius was inclining to Britannicus rather than Nero Agrippina sought the advice with a certain Locusta, a woman of not only a shady, if not evil reputation, but also a known expert in poisons.
Claudius died suddenly. Nero, nor Britannicus, succeeded him.

Nero was highly educated, and his tutor was a famous philosopher and writer, Lucius Annaeus Seneca (5 BC - AD 65).
For five years the government was directed by Seneca and Burrhus, the prefect of the praetorian guard, whose support had ensured the succession of Nero. These initial five years were such of good, competent government and stood in stark contrast with the notorious period which was to follow.
Britannicus soon died in suspicious circumstances.
A breach opened up between the ministers and Agrippina, who found her influence with her son slipping away, and tried to recover it by means which only made the young man resent it more.
Meanwhile Nero became infatuated with Poppaea Sabina, who was to become one of the worst influences of his life.
He had his mother killed in AD 59, and divorced his wife Octavia, then married Poppaea Sabina who later died from his brutality.
Nero, by then clearly deranged, continued to reign for nine gruesome years.
The reign of Nero saw the confirmation of the Roman dominion in Britain, by the campaigns of Suetonius Paulinus in Wales and by the crushing of the great revolt of the Iceni in the eastern area under their queen Boadicea.
Still more familiar is the story of the Great Fire of Rome in AD 64, when half Rome was burnt to the ground while Nero gave himself up to the emotional joys of the thrilling dramatic moment, and then sought to recover his popularity with the mob by illuminating his gardens with a public display of burning Christians, on the pretence that they had set fire to Rome.
Roman sentiment was especially scandalized when the emperor gloried in taking personal part in public competitions which to Roman eyes were fit only for Greeks, or freedmen, as well as the shamelessness of his vices and extravagances. No man was safe, whose character earned the dislike of the emperor or whose wealth excited his desire.
In AD 67 the Jewish revolt broke out, which saw Nero dispatch Vespasian to put down the rebellion.
Eventually it became all too much and the old soldier Servius Sulpicus Galba raised his standard in revolt in Spain against a despised emperor.
Galba, a rigid old warrior, marched on Rome. Nero found himself deserted on all sides and killed himself.

Galba was hailed emperor but displayed such petty meanness and lack of generosity to the soldiery that the army in consequence transferred their allegiance to Marcus Salvius Otho and Galba was slain after only a reign of six months.

Otho was hailed emperor in January AD 69, but the legions of the Rhine preferred their own commander Vitellius, for no better reason than the fact that he was their commander.
Vitellius' generals defeated Otho's troops at Bedriacum (Cremona) and Otho duly committed suicide.

Vitellius entered Rome and took the throne in AD 69.
But his reign, too, was not to last. For in the east Vespasian arose in revolt, being hailed emperor in Egypt and Syria.
The troops along the Danube sided with him and general Antoninus Primus led an army into Italy, defeated Vitellius' forces and the second Battle of Bedriacum (Cremona) and marched on Rome.
Vitellius was dragged through the streets, tortured and alas flung into the river Tiber.

Thus with the fall of Vitellius came the end of the first crisis of the Roman empire. With it was revealed the fundamental weakness from which the empire could never completely escape. So long as the troops held to their allegiance their emperor was an incredibly powerful figure. While he lived there was no-one they could transfer their allegiance except their immediate commander if he chose to accept it. Once an emperor was firmly established with general consent he needed not to fear revolt unless he made himself wantonly intolerable. But the settlement of the succession lay with the soldiery and primarily with the praetorians, in their camp at Rome.

Vespasian arrived in Rome to take power in AD 70, having been represented in Rome by his younger son Domitian until his arrival.
Vespasian's men were loyal. There was no possible rival on the scene. Rome only craved for the anarchy to end so Vespasian's formal recognition as emperor was a foregone conclusion.
Vespasian was a practical man. Like Marius he was of the people, an in no way ashamed of the fact.
He had been fighting, commanding troops organizing and administrating for thirty years, hence he knew the system by personal experience. More so, he was a shrewd judge of character and knew the empire form end to end.

In the same year, in September AD 70, Jerusalem finally fell to Titus, Vespasian's' elder son who had taken charge of the Jewish campaign, as his father had left for Rome. The great Temple of Solomon was razed, the Jews were driven out of their homeland and dispersed.
Also in AD 70 a short lived rebellion in Germany, led by Gallic legionary officer Civilis. It is noteworthy as it proved just how well Vespasian had restored order in such short a time. Unlike during the previous time of civil strife, rebellions now had little chance of prospering.

The vices and extravagances of Roman society held no attraction for the gritty soldier.
His hard-headed shrewdness was the best possible answer to the corruption of the times, making decency more fashionable than indecency.
Vespasian indulged in no violence and restored law and public confidence.
He was well served in the men he appointed and his public works were directed to the dignity of state and the welfare of the people. Meanwhile his expenditure was economical and put the state treasury back on a sound footing.
Vespasian was not picturesque, but he was effective and he gave the empire, and above all the heart of the empire, Italy, that peace and order which had been to rudely shaken during the civil war.

Titus had been for some years formally associated with his father as co-emperor and succeeded him as a matter of course in AD 79. He reigned for only two years, long enough though to win a lasting reputation, hardly expected at the time of his accession, for clemency and generosity. He was emperor at the time of an appalling calamity for which there had been no precedent, the utter obliteration of the cities of Herculaneum and Pompeii by an eruption of the volcano Vesuvius in AD 79.

Titus left no son and was hence succeeded by his brother Domitian in AD 81, who left to posterity a reputation among the worst of all Roman emperors. The combination of personal depravity with superstitious fanaticism in him led to disaster. It drew him into the encouraging of some vile people and the revival of many of the worst excesses of Nero's reign, oddly accompanied by social legislation of the puritanical kind.

At the outset Domitian sought military glory, but his participation in frontier campaigns achieved little.
The most creditable feature of Domitian's reign was the governorship of Britain by Gnaeus Julius Agricola (AD 37-93), for which though Domitian was not responsible, but which he jealously terminated in AD 85.
Agricola had been appointed to Britain by Vespasian in AD 78 and had since not only advanced the border to the line from the Solway Firth to the Tyne (the later position for Hadrian's Wall), but also partially subjugated the lowlands of Caledonia and advanced into the Highlands and there inflicted a heavy defeat on the Picts.

Domitian excited less terror but hardly less disgust in his latter years than Nero. Rome endured him with growing anxiety and displeasure, but only one serious revolt was ever attempted against him. Lucius Antoninus Saturninus who was in command of two legions along the Rhine, tried to follow the example of Galba, but was quickly overthrown by another officer.
The only effect of the rebellion was to increase the suspicion and fears of the emperor and intensify the worst traits of his character.
Bad as he was, no one wanted a renewal of the armed contests for the position of emperor.

However, a major plot against Domitian, including the praetorian prefects, several senators and even the emperor's wife, succeeded and the hated emperor was assassinated.